1. Field of the Invention
This invention relates to an improvement in a magnetic recording tape cassette, and more particularly to an improvement in a tape pad for a magnetic recording tape cassette.
2. Description of the Prior Art
As is well known, a magnetic recording tape cassette such as a compact type tape cassette is provided with a tape pad for backing the recording tape against the magnetic head of a recording/reproducing system. The tape pad is urged toward the recording tape to resiliently press it against the magnetic head when the magnetic head is inserted into the cassette. In an open-reel type tape recorder, the recording tape is brought into intimate contact with the magnetic head by appropriately setting the tape feeding path. However, in the tape cassette where the tape is not drawn out from the cassette, it is difficult to set a tape feeding path suitable for bringing the tape into intimate contact with the magnetic head. Therefore, a tape pad is employed in the tape cassette to bring the tape into intimate contact with the magnetic head.
The tape pad is generally formed of felt and is supported on a resilient leaf spring at the center thereof. Conventionally, the leaf spring is stamped out of a resilient plate member such as of phosphor bronze and is like a cross in its shape, comprising a rectangular central portion to which the felt tape pad is attached and a pair of strip-like arm portions extending from the central portion on either side thereof, each arm portion being narrower than the central portion. The leaf spring is mounted in the cassette so that the arm portions extend substantially in parallel to the recording tape. The conventional cross-like pad supporting member or the leaf spring has a problem in that it is apt to cause uneven wear of the magnetic head. It is difficult to obtain a pad supporting member having a prefectly flat pad supporting surface on the central portion thereof. For example, when the supporting member is stamped out of a resilient plate member, it is apt to deform so that the upper portion and the lower portion thereof are bent in different directions. When the tape pad is attached to the uneven pad supporting surface, the contacting force with which the tape pad is pressed against the magnetic head inherently varies with the portion of the pad. For example, the contacting force at the upper portion of the pad becomes different from that at the lower portion thereof, whereby the magnetic head is unevenly worn. Such unevenness in the contacting force can also be caused when there are manufacturing errors in the measurements of the cassette half on which the pad supporting member is mounted, or when the magnetic head is inserted into the cassette in an incorrect position with respect to the tape pad. In the recording/reproducing system using the cassette, recording and reproducing are generally carried out in two directions of the recording tape. Therefore, the magnetic core of the magnetic head is brought into contact with the recording tape at a position laterally shifted from the longitudinal axis of the tape. Further, the part of the magnetic head other than the magnetic core is more liable to be worn than the magnetic core. Accordingly, if the unevenness in the contacting force of the tape pad is such that the contacting force at such other part of the magnetic head is larger than that at the magnetic core, the difference between the wear at the other part of the magnetic head and the wear at the magnetic core is significantly enlarged.